Each share of the issuer's Series AA Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's firm commitment underwritten initial public offering pursuant to a registration statement on Form S-1 under the Securities Act of 1933, as amended (the "IPO"), and had no expiration date.

(2)

Vulcan Ventures Incorporated ("VVI") is the Managing Member of Vulcan Capital Venture Capital Management I LLC, which is the Manager of Vulcan Capital Venture Capital I LLC ("VCVC I"). Paul G. Allen has sole voting and investment power of the shares held by VCVC I. VVI and Mr. Allen disclaim beneficial ownership over the securities held by VCVC I except to the extent of their respective pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.

(3)

Each share of the issuer's Series AA-1 Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(4)

Each share of the issuer's Series B Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(5)

Each share of the issuer's Series B-1 Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(6)

Each share of the issuer's Series C Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(7)

Each share of the issuer's Series D Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(8)

Each share of the issuer's Series E Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(9)

Each share of the issuer's Series A-2 Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(10)

VVI is wholly owned by Paul G. Allen, and Mr. Allen has sole voting and investment power of the shares held by VVI.

(11)

Each share of the issuer's Series A-3 Convertible Preferred Stock converted into 1 share of the issuer's Common Stock on May 15, 2012 pursuant to an election by the holders of a majority of the shares of the issuer's preferred stock in connection with the closing of the issuer's IPO, and had no expiration date.

(12)

VCVC I exercised the warrant in full in connection with the closing of the IPO. The warrant expired upon the closing of the IPO if not exercised.

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